How Much Alcohol Is In This? | Measuring ABV
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- Опубліковано 10 гру 2017
- Whenever someone drinks a beer that you made, they're bound to ask you how much alcohol it has. Maybe they're worried about whether or not they'll be able to drive later, or maybe they want to drink to forget. Either way, in this video, I'll show you how I measure the amount of alcohol in the beer I make.
As you probably already know, the alcohol content of a drink is expressed as %ABV, or Alcohol By Volume. This is exactly what you think it is - the percentage of the volume of each serving that is ethyl alcohol - sweet, delicious ethyl alcohol.
To compute the ABV, we need to understand specific gravity. Specific gravity is a unit-less measure that, in the context of brewing, compares the density of the brew to the density of water. So, the more sugar that's in the brew, the more dense it will be, and the higher the specific gravity.
At this point you should realize that the specific gravity of the brew will be different before and after fermentation, since the yeast will convert some of the sugars into alcohol. Anyway, the gravity measurement prior to fermentation is called the "Original, or Initial, Gravity" and the gravity reading taken after fermentation is called "Final Gravity".
So, the basic idea when computing the ABV is to compare the Final Gravity to the Original Gravity, so we'll know how much of the fermentable sugars were converted into alcohol. This means you'll need to take two measurements, so, if you've already started fermenting and didn't measure the original gravity, sorry, I can't help you.
So how do we go about doing this?
There are two common tools available to the home brewer. One is a hydrometer. It costs around $10 US or 9 Euros. It uses a weighted bob with a scale printed on the side. To use it, just sanitize the vessel and fill it with enough liquid to make the bob float. Then read the specific gravity directly off the scale.
The other is a refractometer, which sounds fancy, but it isn't really. After all, it's just a piece of glass and some plastic. They're not too expensive either. One like this can be purchased for about $20 US. It uses a prism to measure the amount of sugar in the liquid and report it in degrees Brix.
So, what is Brix?
Brix is a measure of the of a liquid's sugar content, with one degree of Brix equivalent to a 1% sucrose solution as a percentage of mass. Also, Brix is named after Adolf Ferdinand Wenceslaus Brix, who is apparently... dead.
To use it, place a couple of drops on the prism, hold it up to the light, and read the Brix value. Also, be sure to take the initial and final refractometer readings at the same temperature, because apparently that matters.
Now that we have our Brix value, we'll need to do some arithmetic to convert it to specific gravity.
SG = (Brix / (258.6 - ((Brix / 258.2) x 227.1))) + 1.0
Quick aside: There are actually three common scales for measuring sugar density. They are the Balling, Brix, and Plato scales, with each being a slight improvement to the one before it. However, the differences are so small that, for our purposes, they are interchangeable.
By the way, degrees Plato is not named after this guy, but after Fritz Plato, who, like Adolf Brix, is also dead.
Which one should you use. Personally, I prefer the refractometer. This is because I typically brew in small batches and it takes quite a bit of beer to fill the hydrometer far enough for the bob to float.
So, once you have your two specific gravity measurements, just plug the values into this equation:
ABV = (FG - OG) x 131.25
Or, at least that used to be the equation. Now, apparently everyone prefers this formula because it is slightly more accurate. Apparently.
ABV = (76.08 x (OG - FG) / (1.775 - OG)) x (FG / 0.794)
There's other variations on these formulas, but unless you're calculating ABV for the purpose of complying with certain legal requirements, these should work well enough.
Let's work these equations for my most recent brew. I'll have Google do the arithmetic for us.
Measuring with the refractometer, I got 16 point something degrees Brix before fermentation, so that gives me an original gravity of ... 1.06543239677
After fermentation I got a Brix reading of approximately 10. Doing some more arithmetic gives me a final gravity of ... 1.04003130566
Now that we have our initial and final gravity numbers, just plug them into the ABV formula. Not that one. This one.
It looks like this brew is a rather tame 3.6 percent alcohol by volume. Well, that's quite disappointing. Oh well.
There you have it. I wanted to keep this video short and to the point. I'll put the equations, as well as links to the equipment in the video description. If you found this video useful, please hit that "like" button. If you didn't, you don't need to do anything at all. Thanks for watching. - Навчання та стиль
Note: There is a typo at 4:08. It should say 1.040 for the Final Gravity and not 1.0040.
And as a person who doesn't know anything about math I calculated%8 something I found websites and let the brewing calculators calculate it for me and I went mad every time I found 8 then I said to myself: YOU KNOW NOTHING JOHN SNOW YOU KNOW NOTHING. And finally I considered reading the comments by luck.
Great video! Just what I need for my micro brewing as to not waste any. Thanks for posting.
Great video! I don't know if you can in the first place, buy do you know if it's possible to just measure alcohol content after fermentation? I heard something about this while researching how to use a refractometer.
Great 👍 vide bud ! Thx
but a refractometer needs an alcohol correction factor , doesn't it ? that is ; a FG reading is no longer accurate through the lens because the alcohol has affected the reading right?
That was an excellent video! Thanks for all the work.
If it's specific gravity could(n't) you weigh original product Vs. final product in specific unit(i.e. tablespoon full volume) on balance scale. Find scale of value & mark respectively on scale. Would that work. More alcohol lighter weight/s.g.?
Noted. Thanks for the math lesson!
Mad scientist! 💥👌💪
Bruuuh
At 3:25 you give a formula that is said to be more accurate. Where does this formula come from? I've always used the first formula that you gave thinking it was the best one to use. Punching in all the appropriate numbers yields a difference of 0.8% ABV for my homemade wine. This I consider a significant difference. If you could, please let me know where this second formula comes from. Thanks.
HELLO, :D
Can i have a link to more info about the formula used to claculate de abv?
Thank you so much ! I am from Saudi Arabia the only one i could find here is a refractometer to measure my Distilled spirit .. I couldn't find a hydrometer so I guess I will stick with the refractometer ... thank you again your video very useful
You're very welcome.
The refractometer for alcohol measurement is different from the one for sugars.
Im from Saudi and i have an extra hydrometer if you need it :)
Does the Brix-SG calculation used here take into account the refractory deviation caused by the increasing presence of alcohol during fermentation?
John Hayes no, thats wrong. You have to measure it by compairing the SGravity which is given by the hydrometer.
I'm so confused!! If the refractometer read 1016 how did you get 1006.? And the fg said 10 but the number was 1004. I dont understand, could you help me w this please? Thank you so much.
Can I use it to calculate ABV in my Kombucha? I don't 2F hard booches in my Kombucha
Except you can't use a refactometer for the final gravity as it is affected by the alcohol so you need to use a different formula or use a hydrometer
thaanks
Thank you for this video, sorry you ended up brewing sparkling water.
Imma use this to test my kombucha abv :)
Me, too, but only my 2F hard booches
@@Tofu_Pilot do you have a good recipe for hard booch which can share here?
Please
1/how to measure alkahol in vinegar
2/this process can to measure alcohol less than 1% example 0.2 or 0.02 or less
i always used bread yeast to brew and my stuff was always pretty strong. next time i will try to measure it.
If you liked it w bread yeast, you will probably love it even more with the proper yeast. 😉🍻
@@lilymcalister1825 since then i did maybe 2-3 batch of hydromel and even some red wine with some commercial yeast. its got a very very faint taste, but a unique taste. i personally like the bread yeast taste. i dont think i will buy more commercial wine yeast when i run out. as it is more expensive and not available here except online.
Brother uuuugh
@@brandoncorwin5857 search on youtube, many tests were made and most often bread yeast give a better taste and finished product then the "real" brewing yeast.
What I got out of this video is that coming up with measurement units is a leading cause of death among chemists
I do not understand, i do not have a brix scale on my refractometer when i look in it only has a similar scale going from 0 to 80% and my control substance (JD honey 35%) is showing up as off the scale. I am extremely confused as to how to use this refractometer doesnt have a brix scale.
the refractor is sold for different things. for example i have 2 one for abv and one for brix. i cant interchange them bc the scales, so you need to buy the refractor buit with a scale for what you need. for example i cant use my brix refractor to determine abv. bc the scale is different. But redractors are not as accurate as this video claims. you can test the inaccuracy of the refractor by using store purchased spirits and checking with tye abv on the label. athe refractor is off multiple times.
You cant use a refractometer for FG. Fail!
Hi there Mike! I now this is an old video but I wanted to give it a try an recalculate your numbers but this time using the Homebrew Refractometer calculator at www.northernbrewer.com/pages/refractometer-calculator, and turns out that the number I got was ABV 5.327%, not 3.5% haha, but I would like to confirm this number with you. What do you think? Are you using a different method right now? I'm about to use that calculator for the first time and just want to make sure I get the right number haha. Thank you!
1:08 oh wow.... I previously understood nothing!
Um, not sure what equations you're using, but if your brew was a 1.065 OG and dropped to a 1.004 FG, thats more in the ballpark of 8.0% ABV.
There are other equations you must use to calculate the true Final Gravity if using a refractometer, as alcohol skews the FG reading. . which is what I'm trying to figure out!
ABV = (76.08 * (OG - FG) / (1.775 - OG)) * (FG / 0.794)
ABV = (76.08 * (1.06543239677 - 1.04003130566) / (1.775 - 1.06543239677)) * (1.04003130566 / 0.794) = 3.56742627877
It looks like you inserted an extra zero. The only "extra" equation is the one to convert from Brix (or whatever your units are given by your refractometer) and specific gravity. That is also given in the video:
SG = (Brix / (258.6 - ((Brix / 258.2) x 227.1))) + 1.0
You, my friend, have added the extra zero. 4:08
Haha I see in the calculator screen shot right before that you got 1.040. Not 1.004.
Original Gravity of 1.065 and final of 1.040, sounds like she needs somemore yeast!
I was thinking the same thing. 1.004 would be way higher ABV.